Well, for starters, there are loads of British accents, you can go less than 10 miles anywhere in the UK and already be hearing different accents. Usually Received Pronunciation ( RP) accents, those in and around London are easily understandable but yes, there can be loads of accents in the UK that are hard to understand. The accents of Newcastle and Yorkshire come to mind- those who are not native speakers of English, or those not born and raised in England usually have a pretty difficult time with them. What are you having trouble with? do you interact with people from Britain a lot?
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